Micro-LED Reflective Cavity Structure for Light Extraction
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Solution Overview
Problem
Display devices with micro-sized light-emitting diodes face challenges in improving light extraction efficiency due to limitations in forming a reflective structure that effectively reflects light from the side surfaces of the light-emitting diodes.
Innovation Solution
A display device design featuring a substrate with light-emitting elements and transistors, a first organic insulating film with a recessed cavity, and a reflective layer covering the cavity's sides and bottom, enhancing the area of the reflective layer facing the side surfaces of the light-emitting elements to improve light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective structure is formed to reflect light from the side surfaces of the light-emitting diode, then light extraction efficiency is improved, but the device thickness increases
Solution Approach 1:
The invention transitions from a planar reflective structure to a three-dimensional cavity structure that extends vertically into the insulating film. By forming a cavity with depth, the reflective surface area is increased without proportionally increasing the overall device footprint, effectively utilizing the third dimension to improve light extraction while managing thickness constraints
Solution Approach 2:
The cavity structure is formed within the existing insulating film layer, nesting the reflective structure inside the insulating material rather than adding it as a separate external layer. This approach utilizes the available space within the insulating film to create the reflective cavity, reducing the need for additional thickness
2Length of stationary object
If the reflective structure height is limited by display device thickness, then device compactness is maintained, but light extraction efficiency improvement becomes difficult
Solution Approach 1:
The cavity structure concentrates the reflective function in a localized region with enhanced surface area. By creating a cavity with vertical walls and a bottom surface, the reflective area is locally increased at the cavity position, providing improved light extraction efficiency in a compact footprint without requiring uniform thickness increase across the entire device
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design increases the area of the reflective layer facing the side surfaces, effectively reflecting light output from the side surfaces towards the display surface, thereby enhancing light extraction efficiency.
Implementation Method 1
a reflective layer provided covering a side and a bottom of the cavity formed in the first organic insulating film... effectively reflecting light output from the side surfaces toward the display surface
Data Source
AI summary
A display device includes a substrate, a plurality of light-emitting elements and a plurality of transistors provided to the substrate, a first organic insulating film that is provided covering the transistors and is in direct contact with at least one of a source electrode and a drain electrode of the transistors, an anode electrode provided on the first organic insulating film and electrically coupled to each of the light-emitting elements, a cavity formed in the first organic insulating film and recessed toward the substrate, and a reflective layer provided covering a side and a bottom of the cavity formed in the first organic insulating film.